The present invention concerns a liquid ring pump that has a passage which scavenges gas trapped in a rotor bucket of a liquid ring pump after the bucket has swept past a closing edge of an outlet in a port plate and before the bucket opens into an inlet of the port plate. The passage is in the port plate angularly between the closing edge of the port plate outlet and the leading edge of the port plate inlet.
Liquid ring pumps are well known. Generally a liquid ring pump includes a housing; a rotor within the housing; a shaft extending into the housing on which the rotor is fixedly mounted; and a motor coupled to the shaft. During operation, the housing is partially filled with operating liquid so that when the rotor is rotating, the rotor blades engage the operating or pumping liquid and cause it to form an eccentric ring that diverges and converges in the radial direction relative to the shaft. Where the liquid is diverging from the shaft, the resulting reduced pressure in the spaces between adjacent rotor blades of the rotor assembly (buckets) constitutes a gas intake zone, low pressure zone. Where the liquid is converging towards the shaft, the resulting increased pressure in the spaces between adjacent rotor blades (buckets) constitutes a gas compression zone
U.S. Pat. No. 4,850,808, Schultze, recites that in a conically or cylindrically ported liquid ring pump, compressed gas that would otherwise be carried over from the compression zone to the intake zone of the pump is made to bypass the intake zone by passing through a first aperture in the port member into a clearance between the rotor shaft and the port member and then through a second aperture in the port member from the clearance to an initial portion of the compression on zone.
U.S. Pat. No. 5,769,609, Plescher, recites that in a liquid-ring compressor having a rotor mounted in a compressor housing, the rotor is mounted eccentrically relative to the center axis of the compressor housing. At least one control disk is arranged on one of the end faces of the rotor. The control disk is provided with a suction slot and a pressure slot for the feed and discharge of the medium to be compressed, respectively. The control disk also has an encircling distribution groove in the area covered radially by the hub of the rotor. Operating liquid is introduced into a feed opening, which leads to the distribution groove, to seal an axial gap between the control disk and the rotor hub. A blocking element projects radially into the distribution groove and is provided on the side of the feed opening that has the greater pressure differential between the pressure of the operating liquid entering the feed opening and the pressure in the rotor cells. The blocking element improves the sealing of the axial gap.
U.S. Pat. No. 6,354,808, Shenoi, recites that liquid ring pumps, of the type having a port structure that extends into an annular recess in an end of the rotor, have several parts that are designed so that they can be used to make pumps having either relatively demanding service requirements or substantially less demanding service requirements. Some of these parts can be substantially exactly the same in both final pump configurations. Others of these parts may be castings that differ substantially only in some subsequent machining in order to adapt them for each final pump configuration. Some of the final pump configurations have more compact mechanical seal structures and/or improved structures for supplying liquid to the seal structures.
International publication WO 2010 071651 is directed to a liquid ring pump that has a channel in a portion of a liquid ring pump. The channel has a first opening which opens into a first bucket formed by rotor blades. The first opening is located along an arcuate path between a closing edge of an inlet port and a leading edge of a discharge port. The inlet port and discharge port are in a port plate of the liquid ring pump. The channel has a second opening which opens into a second bucket formed by rotor blades. The second opening is on an arcuate path between a closing edge of the discharge port and a leading edge of the inlet port. A fluid pathway interconnects the first and second openings. At least a portion of the liquid ring pump forming the channel is disposed in a circumferential cylindrical cavity, wherein the cavity is formed from a plurality of axially extending rotor blade ends. The portion of the liquid ring pump providing the channel can be a removable cylinder. The channel is isolated and sealed off from the discharge port and the inlet port of the port plate when the pump is in the running mode.